1. Field of the Invention
The present invention relates to textiles in general, and in particular to a device for the application of a liquid treating composition uniformly over the width and along the length of a traveling textile yarn made up of a plurality of individual filaments.
2. Prior Art Statement
In the manufacture of synthetic fibers, it is generally required to apply a lubricating liquid composition as soon as possible after the filaments have been solidified. The purpose of this lubricating liquid is to reduce friction against other fibers and against elements of processing machinery, as well as to lower the surface resistivity of the fibers, thereby reducing the static electric charge thereon.
However, uniformity of appliction of the liquid treating composition has not been achieved through the utilization of devices of the prior art. By far the most widely employed of such devices is one which comprises a ceramic roll which, partially submerged, rotates in a pan containing the liquid to be applied. The fibers or yarns are caused to travel over, and to contact the non-submerged surface of this roll, picking up adsorbed liquid therefrom. (See, for example, U.S. Pat. No. 3,549,740, which is among many recently devised processes which still employ this basic device). The lack of uniformity in the application of liquid treating compositions by means of these and related prior art devices is evidenced by undesirable, wide variations in the amount of treating agent actually found in identical yarns separately treated by identical devices. That such variations are unacceptable is clear in view of today's requirements for greater uniformity in finished products, as well as enhanced speed and efficiency in manufacturing operations.
The closest prior art is considered to be British Pat. No. 1,478,480, which discloses an apparatus for the quantitative application of a liquid agent in a thin layer to fibers or filaments moving uniformly along a linear path. This apparatus comprises a liquid container having an inner compartment equipped with a feed pipe for the liquid agent. The inner compartment opens into a slit which is perpendicular to the path of the fibers or filaments. The outlet of the slit is defined by walls which are either uniformly curved concavely or provided with two or more concave recesses. Such a curvature of the slit is required in order to ensure uniform application of the liquid agent.
The present invention differs from that disclosed in British Pat. No. 1,478,480 in certain significant aspects. First of all, it is essential that the elongated sides of the slit are parallel straight lines, contrary to the teachings of the British patent. Secondly, it is essential that the device of the present invention is provided with means for configuring a traveling textile yarn in a close-packed monofilamentary layer and directing the so-configured traveling textile yarn over the slit and in contact with the chamber at a point downstream of the slit and in proximity thereto. Such ensures that: (a) liquid treating agent is in fact forced into the traveling yarn and not drawn thereto by aspiration; (b) uniformity of application of the liquid treating agent is achieved across the threadline, along the threadline, and from threadline to threadline; and (c) there is minimal abrasion of fiber surfaces, which could otherwise be severe as a result of direct contact thereof with the edges of the slit, especially after extensive use of the device. None of the above limitations nor the advantages of their employment are suggested by the disclosure of British Pat. No. 1,478,480.